1. Field of the Invention
The invention relates to a liquid ejecting apparatus that is provided with a tank accommodation unit for accommodating sub-ink-tanks that are connected to a main ink tank through ink tubes.
2. Description of the Related Art
There are cases where ink jet printers must deal with the printing of relatively large amounts of ink. For example, as shown in Japanese Patent Laid-Open No. 2002-307712, there are cases where sub-ink-tanks are provided on a print head unit that has an ink ejection portion that ejects ink, and main ink tanks, which supply ink to the sub-ink-tanks, are provided separately on the main body of the printer. The sub-ink-tanks of the print head unit and the main ink tanks are connected by ink supply tubes that form ink supply pathways. Herewith, each of the inks from ink retention units of each of the main ink tanks is separately supplied to the sub-ink-tanks through the set of ink supply tubes.
And, for example, a serial ink jet printer carries out the printing of ink by way of the print head unit ejecting ink on the printing surface of a print medium while a carriage, in which the aforementioned print head unit is detachably mounted, moves back and forthwith respect to the print surface of the print medium. As for such serial printers, when performing the supply of ink to the print head unit, there are cases where a change of the ink pressure inside the print head unit occurs, due to acceleration and deceleration that comes along with back and forth movement of the carriage. In a case where an ink pressure variation has occurred, there is a danger that the ejection of ink at the ink ejection portion of the print head unit will become unstable. In particular, in the case where the carriage reciprocates at a high speed for the purpose of high speed printing, the influence of ink pressure variation, caused by acceleration and deceleration, becomes larger.
As a solution to this problem, as described in Japanese Patent Laid-Open No. 2002-307712, it is proposed to mount sub-ink-tanks in the print head unit, which sub-ink-tanks have pressure regulation parts that regulate ink pressure.
By way of providing a negative pressure generation mechanism as a pressure regulation part at the portion of the ink ejection unit of the print head unit that is on the upstream side, the ink ejection portion can eject ink without being effected by pressure variation of ink inside the print head unit, caused by the back and forth movement of the print head. Therefore, in printers of this type space is necessary for sub-ink-tanks to be disposed inside the print head unit.
In printers such as that mentioned above, a needle of a needle holding member provided at one end of an ink supply tube (see Japanese Patent Laid-Open No. 2002-307712) is capable of being inserted and removed, through a sealing member, into and out of a needle acceptance portion of the print head unit, which needle acceptance portion is in communication with the sub-ink-tank. In the case where a replacement is necessary, for example, a case where a failure has occurred in the print head unit, or a case where the duration of use of the print head unit has reached its lifespan, in order to replace the print head unit, the needle of the needle holding member is removed from the needle acceptance portion of the print head unit. On the other hand, in the case of carrying out the connection of needles and the needle acceptance portion, through the sealing member, the full load, along the direction of insertion of the needle, which is caused by friction between the tips of each of the needles and each of the contacted surfaces of the sealing members, acts on the contour portion that forms the needle acceptance portion of the print head unit. In doing so, it is necessary that damage to the printer main body and the print head unit due to the insertion force of these needles, and problems such as ink leakage between the needles and the needle acceptance portions, do not occur.
Additionally, for example, as set forth in Japanese Patent Laid-Open No. 2006-255965, an apparatus is proposed wherein ink inside each of the main ink tanks is supplied to the print head unit through an ink supply tube group, via the pressurized air of a pressure pump.